Stationary ELM-free H-mode in ASDEX Upgrade
Abstract
A stationary H-mode without edge localized modes (ELMs) has been recently achieved in the ASDEX Upgrade tokamak by applying central electron cyclotron resonance heating above the L-H power threshold with adequate fueling. It is naturally obtained in favorable ∇B configuration and has several features which are desirable for future reactors, such as dominant electron heating, low input torque, possibility of access at low input power, good energy confinement ( $H_{\mathrm{98y2}} = 0.9{-}1.3$ ), high density ( $f_{\mathrm{GW}} = 0.8{-}0.9$ ), and no impurity accumulation despite the absence of ELMs. This regime is similar to the EDA H-mode and always features an edge electromagnetic quasi-coherent mode which seems to be responsible for enhanced transport losses, as its appearance and disappearance are correlated with changes in edge and divertor parameters.
- Publication:
-
Nuclear Fusion
- Pub Date:
- May 2020
- DOI:
- 10.1088/1741-4326/ab7d1b
- Bibcode:
- 2020NucFu..60e4003G
- Keywords:
-
- ELM-free;
- H-mode;
- quasi-coherent mode;
- high confinement;
- EDA;
- pedestal;
- ASDEX upgrade